Ferrite Coating Design for Near-Ground HF Bowtie Antenna

An effective technique is proposed to extend the impedance bandwidth of a near-ground antenna without significantly degrading the realized gain in this communication. This is achieved by coating the ground plane under the antenna with ferrite tiles. Since the current density is found to indicate the magnetic held and image current density on the ground, ferrite tiles are used to coat the ground plane in regions where there is a high current density concentration. In addition, the end loading is also implemented to extend the bandwidth of the antenna at the lower frequency bound. An HF low-profile antenna is used to verify the proposed method. The height of this antenna can be reduced to 0.023λ using the ferrite tiles, and the lower bound of the bandwidth can be reduced from 7 to 2 MHz. The HF broadband antenna is fabricated, and the measurement is performed to verify the simulated results.